Changing Climate and Forests May Mean More Wildfires

Thursday, Jun. 20, 2013

Drought and precipitation patterns in the state may have an increasing impact on the wildfire season in Utah, researchers at USU's Agricultural Research Station say.

As Utah enters a second consecutive year of drought and temperatures inch upwards, forestry and climate researchers with Utah State University’s Agricultural Experiment Station are predicting conditions that could mean a busy fire season for the state.

According to Michael Jenkins, associate professor in the Quinney College of Natural Resources at USU, drought is one of the biggest predictors of the severity of a fire season. Additionally, recent changes in the precipitation patterns in the state may have an increasing large impact on the wildfire season.

Though Utah continues to receive about the same total amount of precipitation as it has in years past, water today is falling increasingly as rain rather than snow. This shift may lead to warmer and dryer soils, said State Climatologist and USU professor Robert Gillies.

“If there is a lot of snow and the temperatures are relatively cool during the springtime, then the snow melts slowly through the soil,” Gillies said. “If you have a small amount of snow and then it rains, the soil becomes saturated very quickly and the rain just runs off.”

The form that precipitation falls in is not the only thing that is changing for the state; new research suggests that Utah’s climate is warming as well.

“Over the last 10 years the West has been much warmer than the rest of the United States,” Gillies said. “Parts of Utah are well warmer than the global average.”

He added that data predicting a warming pattern may be hard to believe after the bitter cold of winter 2013, but the cold weather in northern Utah was due to temperature inversions that trapped colder air in the valleys and didn’t translate to the mountains where the majority of the state’s snow is stored.

The warming trend that Gillies and other researchers in the Utah Climate Center have been tracking influences many factors that predict the severity of a fire season, including the dryness of underbrush in forests. Underbrush, or “fuel” as fire experts call it, is the initial energy source for wildfires. While the effects of drought are most visible in the dry grasses of the sagebrush steppe, warmer weather also dries forest underbrush — turning parts of Utah into tinderboxes.

The fire season in Utah typically begins in early June. However, changing precipitation patterns and drying fuels may lead to earlier occurrences of fires in future years.

“When the snowpack is shallow like this year, the snow goes away more quickly and the fuels can dry more rapidly,” said Jenkins.

Although some underbrush is normal in a forest, changes in management practices have led to an unnatural buildup of these materials.

“Forests today are in a much different state than they were 200 years ago when fires were more common,” Jenkins said. “We have essentially eliminated any kind of aggressive management in the forests. We have suppressed fires for 100 years, which has allowed fuels to build up, trees to get old, forests to decline and die.”

Jenkins suggests that clearing fuels off of the forest floor is a good place to start fire prevention. Although logging and prescribed fires are the traditional ways of reducing hazardous fuels, they have fallen out of favor in the West due to the disappearance of local timber markets and concerns about carbon emission and air pollution.

According the Jenkins, the future of underbrush elimination may lie in biofuel production. Carbon stored in the dead leaves and wood on the forest floor may be burned in special gasification machines like USU’s own ragon Wagon demonstration unit to produce power.

“It allows us to generate some value and have some economic incentive for forest and woodland manipulations without having to have it all hinge on a timber sale,” Jenkins said.

The likelihood of ignition is another major factor fire experts look at when attempting to predict a fire season. Although humans play an increasing role in the ignition of fires in the West, Jenkins said that two thirds of all fires in the Rocky Mountain region continue to be sparked by lightning strikes.

Gillies’ climate research suggests that changes to the regional climate are producing more extreme weather events. These changes are seen in the fewer, yet harsher storms that occur in both the winter and summer months — including heavy, brief snowfall in the winter and thunderstorms in the summer.

It is not yet known if changes in Utah’s climate will produce an increased number of ignitions from summer thunderstorms, but changes in the severity of winter storms have already been seen.

“We had three or four major snowfalls [in the past winter], which gave us a fair bit of snow in the valley, but it was very small in the mountains,” Gillies said.

He predicts that the likelihood of fire from dry conditions will increase if shifts in winter snow patterns continue.

Though all factors point to a strong fire season, Gillies cautions that it typically takes an accumulation of years with these conditions to produce a wildfire season that is significantly stronger than normal. However, if climate change in Utah continues, Jenkins predicts a lengthening of the fire season.

“We expect that if there is going to be a shallower snowpack going forward, that the fire season could extend on either end,” Jenkins said. “We could get an earlier start because the snow goes away and we could have a later continuation into the fall because the snow is late in coming back.”

Whatever the future of Utah’s climate, Gillies thinks that climatologists are increasingly better prepared to help people and governments anticipate change.

“We have a lot more knowledge of what’s driving our climate and a little bit more predictability as a result,” Gillies said. “That information is starting to get out so that people can prepare…It allows for better management practices.”

Climatologists can now track the many individual weather cycles that determine Utah’s climate.

“We know from our research that precipitation in northern Utah is dominated by a 12-year cycle that consists of two phases — six years of dry and six years of wet,” Gillies said. “We are currently about two years into the dry phase of the cycle. This does not mean that we cannot get a wet year, but overall the conditions will tend towards dry.”

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